[Bda] Perf+toutpleindecarterezo

[Krystal]

hop hop j'ai trouver ca en surfant :

> > > >created something that has massive concurrency in the networking
path in
> > > >SMP.  4 interfaces all constantly raising interrupts kills us
dead.  all
> > > >the hacking of the scheduler and vm and such are just noise when
compared
> > > >to this bottleneck.
>
> I think I mentioned this a long time ago... at high speeds, various NT

> network drivers switch from interrupt-driven to polling.  The
interrupts
> just kill you after some point... and it's pointless to take them all,

> when you could just take a clock interrupt and go fetch packets.
>
> Another thing to think about -- is ways to have CPU/network card
affinity.
> You don't want to be playing L1/2 cache ping-pong on the RAM you use
to
> load the packets off the card.  You hopefully want to use the packets
in
> the CPU that you first read them on.  The way we're restructuring
apache
> will let us plug in whatever extra syscall goop is needed to help
this.
>
> Dean

The original posting doesn't say if the 4 cards shared one interrupt or
not.
Sharing helps a lot under high loads, when your chances of serving two
or three
cards in one interrupt hit may be quite good - assuming the driver is
designed to
do that. The fact he talks about a storm of interrupts suggests they
were
separate.

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Quelqu'un a plus d'info la dessus ?

Krystal